1. Field of the Invention
The present invention relates to an improved gas safety valve that can be automatically shut off when ambient temperature is abnormally high.
2. Description of the Related Art
Taiwan Utility Model Publication No. 239537 issued on Jan. 3, 1995 and entitled "GAS OVERFLOW CONTROL VALVE" discloses a control valve having a plastic insert of low melting point mounted to a front end of a valve body for urging a valve stem in a valve seat to allow gas to pass through an aperture in the valve stem. When the ambient temperature rises, the plastic member melts. The valve stem is biased by a spring such that the aperture in the valve stem is hidden in the valve seat to stop output of gas.
U.S. Pat. No. 5,553,638 issued on Sep. 10, 1996 to Home discloses a cylinder valve insert that is mounted within the outlet of a cylinder valve of a cylinder to allow a fluid to pass through the valve when a male fitting is sufficiently engaged with the outlet, and to prevent such fluid flow when the male fitting is separated therefrom.
U.S. Pat. No. 4,911,194 issued on Mar. 27, 1990 to Lechner discloses a thermally-sensitive coupling device that has a weakened portion mounted to the sleeve member. The weakened portion melts when its temperature is greater than a pre-determined magnitude, such that the sleeve member is incapable of supporting the body. Thus, the valve is shut off to stop supply of gas.
U.S. Pat. No. 5,983,928 issued Nov. 16, 1999 discloses a gas safety valve that can be shut off when a pressure difference between two ends of the ball is relatively high.
The present invention is intended to provide an improved gas safety valve that can be automatically shut off by either an abnormal temperature rise or sudden pressure drop.